The present invention relates in general to the field of electric machines.
An electrical machine of a type involved here includes a housing or stator, a rotor which has a laminated core and which is rotatably mounted in the housing, and a magnetic brake. For its part, the magnetic brake has at least one permanent magnet which is fixed to the housing or stator so that it cannot rotate and is magnetized in an axial direction, an electromagnet which is arranged so that it is connected axially to the permanent magnet and is securely fixed thereto, and a ring-shaped armature which is fixed to the rotor so that it cannot rotate and acts together with the two magnets, wherein the main direction of the magnetic field of the electromagnet likewise runs in an axial direction.
Permanent magnet excited integral brakes, i.e. magnetic brakes, for electric motors usually consist of a permanent magnet and an electromagnet which act together with an armature. The electromagnet or coil body usually constitutes a stator part, while as a rule the armature is realized as the rotor part.
For functional reasons, the rotor part typically has an axially resilient magnetic steel armature and a carrier flange which is usually amagnetic. This multi-part construction results in an additional overall length of the electric motor. In addition, the costs for the components and for assembling the rotor part are high. Finally, the high inertia due to the solid steel armature adversely affects the dynamics of the electrical machine (e.g. servomotor).
It would therefore be desirable and advantageous to provide an improved electrical machine to obviate prior art shortcomings and to include an integral brake which is as small and as cost effectively as possible, and yet ensures high dynamics of the electrical machine.